The present invention relates to the recuperation of septic tank content. More specifically, the present invention is concerned with a method and a system that enable the efficient recuperation of the sludge contained in septic tank.
Owners of residences that are not connected to a conventional sewer system are often forced to comply with local regulation that requires them to install a septic tank.
So called, xe2x80x9cVacuumxe2x80x9d type trucks were developed to literally suck up the sludge from the septic tank and then to dispose it in appropriate dumping sites. However, since the environmental norms have become more rigid in many countries, the management of sludge has become a problem that the governmental and municipal authorities have been trying to overcome. More specifically, means that would permit the reduction of these residual matters at the source, which would promote their reuse as well as valorise them, are being searched.
Still, today considering the costs generated by the dumping of sludge in the appropriate sites and time wasted in transporting the sludge, many contract workers employed to recuperate the content of septic tanks refuse to conform to the regulations, and therefore set up septic tanks almost everywhere in the environment. This, of course, can have unfortunate consequences.
Many technologies are currently available or known in this field. The following is a brief summary of these technologies.
Vacuum Type Truck
This is a system that uses a pump to empty the whole content of the septic tank. This system is generally well accepted by clients and operators, since no liquid is returned to the tank after the recuperation of the septic tank content is over. This system is the most widely used to this day. However, this system comprises several drawbacks. For example, since all of the content must be recuperated and transported to the dumping site, the operation of this system is very expensive in transport and handling costs when the dumping site/plant is situated at a far distance from the client.
Dehydration Type Truck
This is a system that uses a pump as well as a centrifuge unit to generate dryer sludge. The system requires the use of chemical products such as coagulants and/or floculants, and requires also a longer treatment time. Although this process yields the dehydration of the sludge at 90% of the volume to be transported, the sludge is generally not sufficiently dehydrated to be dumped directly in the dumping sites. In addition, the sludge is usually too thick to be poured in a treatment plant, which renders their disposition in appropriate sites difficult. This technology also requires a bulky and long mobile unit, which limits the access to the septic tank. Another drawback of such a system is that it is expensive since the dehydration demands a lot of time and expensive chemical products. The mobile unit is also difficult to operate, hence more qualified labour is necessary.
Double Chamber Vacuum Truck
Double chamber vacuum trucks include a pump that can return a portion of the liquid to the septic tank. The mobile unit sends back the water to the tank without having filtered it. The quantity of sludge to transport is therefore reduced since a portion of the liquid of the septic tank is returned to the tank after the sludge is removed. In addition, the process does not use chemical substances.
However, since no filtration is done before returning the liquid to the septic tank, there is no guarantee that the liquid that is returned does not contain sludge. There is no precise mechanism that indicates to the operator the quantity of sludge that has been retrieved or that has to be retrieved. Thus, the operator can only rely on his experience. Moreover, by returning the liquid that comprises suspended solid in the tank, it gives rise to a risk that, after an influx of water, the suspended solid will end up blocking the purification field. The consequences of such a block are significant, considering that a defective purification field should be reconstructed completely. Another important disadvantage is that the client is bound to a restrictive use of water 12 to 24 hours following the draining of the tank, in order to limit the possibly harmful water influx.
More specifically, in accordance with the present invention, there is provided a method for the recuperation of septic tank content using a mobile recuperation unit having first and second reservoirs, the content of the septic tank including sludge, supernatant and scum, the method comprising:
transferring a portion of the supernatant from the septic tank to the first reservoir of the mobile recuperation unit;
transferring the remainder of the content of the septic tank into the second reservoir of the mobile recuperation unit;
filtering the supernatant; and
transferring the filtered supernatant from the first reservoir back to the septic tank.
According to another aspect of the present invention, there is provided a system for the recuperation of septic tank content including sludge, supernatant and scum, the system comprising:
a first reservoir;
a second reservoir;
a bidirectional pump assembly having at least one pump suction pipe having a proximate end connected to a first port thereof; the pump assembly having a second port connected to the first reservoir and a third port connected to the second reservoir;
a filtering assembly provided between the second port and the first reservoir;
whereby, the bidirectional pump assembly is so controlled as to pump the supernatant from the septic tank into the first reservoir, filter this supernatant via the filtering assembly, pump the sludge and the scum to the second reservoir and pump back the filtered supernatant to the septic tank to thereby reduce the portion of the content of the septic tank remaining in the recuperation system.
According to a third aspect of the present invention, there is provided a system for the recuperation of septic tank content including sludge, supernatant and scum, the system comprising:
a first reservoir;
a first pump having an inlet and an outlet open to the first reservoir;
a first pump suction pipe having a proximate end connected to the inlet of the first pump;
a filtering assembly associated with the first pump suction pipe;
a second reservoir;
a second pump having an inlet and an outlet open to the second reservoir;
a second pump suction pipe having a proximate end connected to the inlet of the second pump;
whereby, a) the first pump may be so controlled as to pump the supernatant from the septic tank to the first reservoir, b) the filtering assembly may be so controlled to filter the pumped supernatant, c) the second pump may be so controlled as to pump the sludge and the scum to the second reservoir, and d) the first pump may be so controlled as to pump back the filtered supernatant to the septic tank to thereby reduce the portion of the content of the septic tank remaining in the recuperation system.
According to yet another aspect of the present invention, there is provided a system for the recuperation of septic tank content including sludge, supernatant and scum, the system comprising:
a first reservoir;
a first pump suction pipe having a proximate end connected to the first reservoir;
a second reservoir;
a second pump suction pipe having a proximate end connected to the second reservoir;
a vacuum pump connected to the first and second reservoirs. a filtering assembly associated with the first reservoir;
whereby, a) the vacuum pump may be so controlled as to generate a partial vacuum in the first reservoir to pump the supernatant from the septic tank to the first reservoir, b) the filtering assembly may be so controlled to filter the pumped supernatant, c) the vacuum pump may be so controlled as to generate a partial vacuum in the second reservoir to pump the sludge and the scum to the second reservoir, and d) the filtered supernatant may be returned to the septic tank via the first pump suction pipe to thereby reduce the portion of the content of the septic tank remaining in the recuperation system.
According to a fifth aspect of the present invention, there is provided a system for the recuperation of septic tank content including sludge, supernatant and scum, the system comprising:
a first reservoir;
a second reservoir;
means for pumping the supernatant into the first reservoir and the sludge and scum into the first reservoir; the pumping means being configured to allow the pumping back of the supernatant into the septic tank;
means for filtering the supernatant;
whereby, the system is so controlled as to pump the supernatant from the septic tank into the first reservoir via the pumping means, filter this supernatant via the filtering means, pump the sludge and the scum to the second reservoir and pump back the filtered supernatant to the septic tank via the pumping means to thereby reduce the portion of the content of the septic tank remaining in the recuperation system.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.